1. Field of the Invention
The present invention relates to an electrical element and an electrical connector, especially to an electrical element and an electrical connector that are electrically connected to a circuit board.
2. Description of Related Art
Nowadays electrical connection points for inputting signals on chips increase along with the increasing of the processing speed and functions of integrated-circuit chips such as central processing unit (CPU). Yet the volume after packaging is getting compact.
In order to catch up with the development of integrated-circuit (IC) chips such as CPU, the electrical connector that connects the IC chips with the circuit board includes more and more terminals with high density. Abundant terminals with high density make how to solder the terminals on the circuit board with good soldering quality become a dilemma. Presently, soldering is the most common way in this field. The electrical connector includes an insulating body, a plurality of terminals received in the insulating body, and a plurality of solder balls corresponding to the terminals. The insulating body is disposed with a plurality of receiving holes and each terminal is received in a corresponding receiving hole. Each terminal electrically connects to the electrical connection points on the IC chips correspondingly. And the electrical connector is soldered to the circuit board by surface mounted technology (SMT).
However, while soldering the solder balls to the circuit board, the solder ball needs to be fixed in the receiving holes in advance. The ways of fixing the solder balls are divided into two groups: one is pre-soldering the solder balls. The solder ball is melted and attached on the terminal in the receiving hole. Then the solder ball is soldered to the circuit board. The other way is that the solder ball is clamped by the terminal. The terminal holds the solder ball and then the solder ball is soldered to the circuit board.
No matter which way the solder ball is fixed, the solder ball is assembled with the terminal firstly and then the soldering is performed. However, all people skilled in this field learn that there are two errors that cause solder ball deformation in the electrical connectors available now. One is generated by the insulating body and the other is caused by assembling. During soldering, the high temperature makes the insulating body warp so that the solder balls in the insulating body are not located on the same plane. Thus dewetting or virtual soldering appears and this leads to the error of the insulating body. Moreover, the abundant terminals with high density is difficult to be the same during manufacturing so that solder balls attached on the terminals are not on the same plane. Due to the above errors, the solder balls have height difference. Thus part of the solder balls are unable to contact with solder paste applied to the circuit board and dewetting or virtual sodering occurs.
Thus there is a need to design an electrical element and an electrical connector that corrects above errors and improve the soldering quality.